Supramolecular Architectures of Metal Complexes Controlled by a Strong pi center dot center dot center dot pi Stacking, 1,8-Naphthalimide Functionalized Third Generation Tris(pyrazolyl)methane Ligand
Reger, DL; Sirianni, E; Horger, JJ; Smith, MD; Semeniuc, RF
| HERO ID | 3575780 |
|---|---|
| In Press | No |
| Year | 2010 |
| Title | Supramolecular Architectures of Metal Complexes Controlled by a Strong pi center dot center dot center dot pi Stacking, 1,8-Naphthalimide Functionalized Third Generation Tris(pyrazolyl)methane Ligand |
| Authors | Reger, DL; Sirianni, E; Horger, JJ; Smith, MD; Semeniuc, RF |
| Journal | Crystal Growth & Design |
| Volume | 10 |
| Issue | 1 |
| Page Numbers | 386-393 |
| Abstract | A new hetero-bifunctional ligand designed to form supramolecular structures with a combination of covalent and noncovalent forces has been prepared. The ligand, (1,8-naphthalimide)CH2C6H4CH2OCH2C(pz)(3) (L-tris, pz = pyrazolyl ring), contains both a tris(pyrazolyl)methane coordination unit and a 1,8-naphthalimide strong pi center dot center dot center dot pi stacking unit. The reactions of iron (II), copper(II), and cadmium(II) tetrafluoroborate salts with 2 equiv of L-tris yield [Fe(L-tris)(2)](BF4)(2) (1), [Cd(L-tris)(2)](BF4)(2) (2), and [Cu(L-tris)(2)](BF4)(2) (3), respectively. Vapor diffusion crystallization yielded two pseudopolymorphs for 1. In the solid-state structures of both forms, the iron is in an octahedral environment with bond distances expected for low-spin iron(II); both tris(pyrazolyl)methane donor sets are in a kappa(3)-coordination mode with each L-tris ligand in a U-shaped, syn arrangement. In one pseudopolymorph, the 1,8-naphthalimide side chains are on the same side of the molecule when viewed down the metal axis (syn-1), twisted only 30 degrees with respect to each other. In the second pseudopolymorph, the side chains are oriented in opposite directions at 180 degrees (anti-1). Both structures are one-dimensional, organized by intermolecular pi center dot center dot center dot pi stacking interactions of the 1,8-naphthalimide units. Each naphthalimide unit reaches past the naphthalimide unit on the adjacent cation leading to a pi center dot center dot center dot pi stack using the face of the naphthalimide unit directed toward its metal complex, interlocking the U-shaped groups. The interaction of the two naphthalimide groups is directionally specific; they are oriented head to tail with substantial overlap of the parallel rings. The twisting of the side chains at 30 degrees for syn-1 leads to a helical structure, whereas the 180 degrees orientation of the side chains in anti-1 leads to a linear structure. The cadmium(II) complex is isostructural to syn-1 and the copper(II) is isostructural to anti-1. Although the supramolecular structures of these two compounds are similar to the matched iron(II) complexes because of the similar orientations of the side-chains and the consistent noncovalent interactions of the naphthalimide synthon, the larger size of cadmium(II) leads to a highly distorted structure about the metal. The copper(II) structure is also distorted, as expected for a d(9) complex. |
| Doi | 10.1021/cg901000d |
| Wosid | WOS:000274757100059 |
| Is Certified Translation | No |
| Dupe Override | No |
| Is Public | Yes |